Lyme Disease
Dr. Emily Kirkpatrick

Many of you may be wondering what all the fuss is about Lyme disease. Everywhere you turn, you see references to it or hear comments about it at the barn. Because Virginia is an area where Lyme disease is prevalent, it’s important that you understand a little about the disease and what it might mean for you and your horse. Lyme disease is caused by a tick-borne spirochete named Borrelia burgdorferi. A spirochete is a type of bacterium that is spiral in shape, hence the name spirochete. This particular one has a life cycle that requires it to live in both ticks and mammals throughout its life. B. burgdorferi is passed from tick to mammal when the tick bites the mammal, however the tick must be attached for 24 hours before transmission can occur. (Remember this, because it’s important when we discuss prevention).
Signs of infection with B. burgdorferi can vary widely from individual to individual. In horses, common signs of Lyme disease are lameness (particularly shifting-leg lamenesses) and hyperesthesia (sensitive to touch). Other signs of Lyme disease can be stiffness, swollen joints, low-grade fever, muscle tenderness and behavioral changes. Diagnosis of on-going disease can be difficult. The best test available today measures antibodies to the organism, and can sometimes be misleading if the horse has been exposed but not infected. The leading researcher of Lyme disease at Cornell University recommends treatment only if there is a positive antibody test and clinical signs of the disease.
Lyme disease is treated with antibiotics- specifically those in the tetracycline family. Doxycycline is the oral antibiotic most commonly used, and treatment lasts for about 1 month. Tetracycline is the intravenous form of the drug, but usage often requires an indwelling intravenous catheter and hospitalization. Herbs and homeopathics can be used to help the horse clear the infection completely, reducing the chance of becoming a chronic carrier. After treatment, re-testing antibody titers can sometimes be helpful in seeing if treatment was effective. However, not all horses have a decline in antibody number after treatment and some horses can be reinfected, even though they may have a high antibody number. Frustrating, I know.
There are lots of ways to try and prevent your horse from getting Lyme disease. Most are not perfect but can be used together. A canine Lyme disease vaccine can be used in horses and has shown some level of protection from the disease, but the studies done in horses are few. The best way to avoid the disease is to keep ticks from latching for more than 24 hours. Frontline spray and some top-spots can be used, but the most reliable technique is to check your horse daily for ticks. Common locations for tick attachment are under the jaw, in the mane and tail, in the armpits and groin area and under the tail. They can also be found inside the ear. You can cut the tail shorter, to about 1 inch above the level of the grass to help prevent ticks from grabbing onto the tail. Remove the ticks carefully and kill them. If you just drop them on the ground, they will crawl right back on!
Lyme disease can be a frustrating disease to prevent, diagnose and treat. It is a common problem in this area and can have a significant impact on your horse’s ability to train and work. If you have concerns about signs of Lyme disease in your horse, call our office today and we can set up an appointment.